1. Field of Invention
The present invention is a digital circuit for prohibiting the improper operation of a vehicle by a physically unfit operator and specifically concerns a circuit for prohibiting the improper operation of a vehicle by such an unfit operator in which a steady control task is imposed on the operator for a designated period of time as a means of evaluating his fitness to operate the vehicle.
2. Description of the Prior Art
The operation of a vehicle, such as an automobile, requires that the vehicle operator be in a mentally and physically stable condition at all times. The ability of a vehicle operator to operate a vehicle is affected by the influence of alcohol, overwork, imperfect health, drugs, and other temporarily disabilitating agents. The operation of a vehicle under such mentally and physically abnormal conditions is extremely dangerous to the person and property of both the operator and the public at large. Devices for determining the unfitness of such operators to operator a vehicle, and for prohibiting the operation of the vehicle involved, has been proposed in the past. In conventional devices of this type, the vehicle operator is given, as a test, appropriate tasks to perform before starting the vehicle into motion. The engine may be started only if the operator shows a sufficient response to the test. Conventional tasks have required the demonstration of an ability to perform simple calculations, tasks which test reflex characteristics or other movement reactions. Among such tasks used for testing, it is known that a steady control task is able to relatively accurately evaluate the fitness of a vehicle operator, and that is is particularly suited for the detection of temporary disability due to the influence of alcohol or other similarly intoxicating drugs. The term "steady control task" refers to a task which requires the continuous maintenance of a designated exertion of a bodily force or position for a predetermined period of time by the vehicle operator, such as, for example, the maintenance of a uniform foot pressure on an operating pedal, such as a brake, clutch, or gas pedal.
In conventional circuits employing a steady control task, evaluation of force to determine whether it is within the acceptable range is extremely complicated and the evaluating circuit typically requires a complex frequency measuring circuit and other such analysis and disposition circuits. This increases the cost of the system, and also increases the number of possible sources of system malfunction. The mandatory characteristics required in a device, which prohibits the improper operation of a vehicle due to temporary operator disability, is consistent and uniform performance, and high reliability. It is clear that the main problem for this type of device is that since its main function is to selectively disable the operation of the vehicle and since the evaluating device must be used in order to start the engine, such a device must have an extraordinarily high degree of reliability. What is needed then is a steady control task apparatus or circuit for prohibiting the improper operation of a vehicle due to temporary disability of the vehicle operator. The device must be characterized by simplicity, low cost and a high degree of reliability.